src/lxc/nl.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <dlezcano at fr.ibm.com>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  */
  23 #include <sys/socket.h>
  24 #include <string.h>
  25 #include <stdio.h>
  26 #include <time.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29 #include <stdlib.h>
  30 #include <linux/netlink.h>
  31 #include <linux/rtnetlink.h>
  32 #include <nl.h>
  33
  34 #define NLMSG_TAIL(nmsg) \
  35         ((struct rtattr *) (((void *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
  36
  37 extern size_t nlmsg_len(const struct nlmsg *nlmsg)
  38 {
  39         return nlmsg->nlmsghdr.nlmsg_len - NLMSG_HDRLEN;
  40 }
  41
  42 extern void *nlmsg_data(struct nlmsg *nlmsg)
  43 {
  44         char *data = ((char *)nlmsg) + NLMSG_ALIGN(sizeof(struct nlmsghdr));
  45         if (!nlmsg_len(nlmsg))
  46                 return NULL;
  47         return data;
  48 }
  49
  50 static int nla_put(struct nlmsg *nlmsg, int attr,
  51                    const void *data, size_t len)
  52 {
  53         struct rtattr *rta;
  54         size_t rtalen = RTA_LENGTH(len);
  55
  56         rta = NLMSG_TAIL(&nlmsg->nlmsghdr);
  57         rta->rta_type = attr;
  58         rta->rta_len = rtalen;
  59         memcpy(RTA_DATA(rta), data, len);
  60         nlmsg->nlmsghdr.nlmsg_len =
  61                 NLMSG_ALIGN(nlmsg->nlmsghdr.nlmsg_len) + RTA_ALIGN(rtalen);
  62         return 0;
  63 }
  64
  65 extern int nla_put_buffer(struct nlmsg *nlmsg, int attr,
  66                           const void *data, size_t size)
  67 {
  68         return nla_put(nlmsg, attr, data, size);
  69 }
  70
  71 extern int nla_put_string(struct nlmsg *nlmsg, int attr, const char *string)
  72 {
  73         return nla_put(nlmsg, attr, string, strlen(string) + 1);
  74 }
  75
  76 extern int nla_put_u32(struct nlmsg *nlmsg, int attr, int value)
  77 {
  78         return nla_put(nlmsg, attr, &value, sizeof(value));
  79 }
  80
  81 extern int nla_put_u16(struct nlmsg *nlmsg, int attr, ushort value)
  82 {
  83         return nla_put(nlmsg, attr, &value, 2);
  84 }
  85
  86 extern int nla_put_attr(struct nlmsg *nlmsg, int attr)
  87 {
  88         return nla_put(nlmsg, attr, NULL, 0);
  89 }
  90
  91 struct rtattr *nla_begin_nested(struct nlmsg *nlmsg, int attr)
  92 {
  93         struct rtattr *rtattr = NLMSG_TAIL(&nlmsg->nlmsghdr);
  94
  95         if (nla_put_attr(nlmsg, attr))
  96                 return NULL;
  97
  98         return rtattr;
  99 }
 100
 101 void nla_end_nested(struct nlmsg *nlmsg, struct rtattr *attr)
 102 {
 103         attr->rta_len = (void *)NLMSG_TAIL(&nlmsg->nlmsghdr) - (void *)attr;
 104 }
 105
 106 extern struct nlmsg *nlmsg_alloc(size_t size)
 107 {
 108         struct nlmsg *nlmsg;
 109         size_t len = NLMSG_ALIGN(size) + NLMSG_ALIGN(sizeof(struct nlmsghdr *));
 110
 111         nlmsg = (struct nlmsg *)malloc(len);
 112         if (!nlmsg)
 113                 return NULL;
 114
 115         memset(nlmsg, 0, len);
 116         nlmsg->nlmsghdr.nlmsg_len = NLMSG_ALIGN(size);
 117
 118         return nlmsg;
 119 }
 120
 121 extern void nlmsg_free(struct nlmsg *nlmsg)
 122 {
 123         free(nlmsg);
 124 }
 125
 126 extern int netlink_rcv(struct nl_handler *handler, struct nlmsg *answer)
 127 {
 128         int ret;
 129         struct sockaddr_nl nladdr;
 130         struct iovec iov = {
 131                 .iov_base = answer,
 132                 .iov_len = answer->nlmsghdr.nlmsg_len,
 133         };
 134
 135         struct msghdr msg = {
 136                 .msg_name = &nladdr,
 137                 .msg_namelen = sizeof(nladdr),
 138                 .msg_iov = &iov,
 139                 .msg_iovlen = 1,
 140         };
 141
 142         memset(&nladdr, 0, sizeof(nladdr));
 143         nladdr.nl_family = AF_NETLINK;
 144         nladdr.nl_pid = 0;
 145         nladdr.nl_groups = 0;
 146
 147 again:
 148         ret = recvmsg(handler->fd, &msg, 0);
 149         if (ret < 0) {
 150                 if (errno == EINTR)
 151                         goto again;
 152                 return -errno;
 153         }
 154
 155         if (!ret)
 156                 return 0;
 157
 158         if (msg.msg_flags & MSG_TRUNC)
 159                 return -EMSGSIZE;
 160
 161         return ret;
 162 }
 163
 164 extern int netlink_send(struct nl_handler *handler, struct nlmsg *nlmsg)
 165 {
 166         struct sockaddr_nl nladdr;
 167         struct iovec iov = {
 168                 .iov_base = (void*)nlmsg,
 169                 .iov_len = nlmsg->nlmsghdr.nlmsg_len,
 170         };
 171         struct msghdr msg = {
 172                 .msg_name = &nladdr,
 173                 .msg_namelen = sizeof(nladdr),
 174                 .msg_iov = &iov,
 175                 .msg_iovlen = 1,
 176         };
 177         int ret;
 178
 179         memset(&nladdr, 0, sizeof(nladdr));
 180         nladdr.nl_family = AF_NETLINK;
 181         nladdr.nl_pid = 0;
 182         nladdr.nl_groups = 0;
 183
 184         ret = sendmsg(handler->fd, &msg, 0);
 185         if (ret < 0) {
 186                 return -errno;
 187         }
 188
 189         return ret;
 190 }
 191
 192 #ifndef NLMSG_ERROR
 193 #define NLMSG_ERROR                0x2
 194 #endif
 195 extern int netlink_transaction(struct nl_handler *handler,
 196                                struct nlmsg *request, struct nlmsg *answer)
 197 {
 198         int ret;
 199
 200         ret = netlink_send(handler, request);
 201         if (ret < 0)
 202                 return ret;
 203
 204         ret = netlink_rcv(handler, answer);
 205         if (ret < 0)
 206                 return ret;
 207
 208         if (answer->nlmsghdr.nlmsg_type == NLMSG_ERROR) {
 209                 struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(answer);
 210                 return err->error;
 211         }
 212
 213         return 0;
 214 }
 215
 216 extern int netlink_open(struct nl_handler *handler, int protocol)
 217 {
 218         socklen_t socklen;
 219         int sndbuf = 32768;
 220         int rcvbuf = 32768;
 221
 222         memset(handler, 0, sizeof(*handler));
 223
 224         handler->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
 225         if (handler->fd < 0)
 226                 return -errno;
 227
 228         if (setsockopt(handler->fd, SOL_SOCKET, SO_SNDBUF,
 229                        &sndbuf, sizeof(sndbuf)) < 0)
 230                 return -errno;
 231
 232         if (setsockopt(handler->fd, SOL_SOCKET, SO_RCVBUF,
 233                        &rcvbuf,sizeof(rcvbuf)) < 0)
 234                 return -errno;
 235
 236         memset(&handler->local, 0, sizeof(handler->local));
 237         handler->local.nl_family = AF_NETLINK;
 238         handler->local.nl_groups = 0;
 239
 240         if (bind(handler->fd, (struct sockaddr*)&handler->local,
 241                  sizeof(handler->local)) < 0)
 242                 return -errno;
 243
 244         socklen = sizeof(handler->local);
 245         if (getsockname(handler->fd, (struct sockaddr*)&handler->local,
 246                         &socklen) < 0)
 247                 return -errno;
 248
 249         if (socklen != sizeof(handler->local))
 250                 return -EINVAL;
 251
 252         if (handler->local.nl_family != AF_NETLINK)
 253                 return -EINVAL;
 254
 255         handler->seq = time(NULL);
 256
 257         return 0;
 258 }
 259
 260 extern int netlink_close(struct nl_handler *handler)
 261 {
 262         close(handler->fd);
 263         handler->fd = -1;
 264         return 0;
 265 }
 266